Without more information (typically obtained during a personal examination, and including height, weight, previous pregnancies and breast-feeding history, breast skin capacity, measurements, etc.) it is not even possible to determine if your anatomy will allow placement of 800cc implants.Generally, I might offer that 800cc in an "average" woman would add about 3 cup sizes to whatever she started with. So, of course, if you actually fill a D-cup bra now, you will be quite large (if in fact your anatomy can accommodate that additional volume). If you simply wear a D-cup bra, don't fill the bra cups, and have adequate skin capacity for 800cc implants, you will still be quite large, and will need to shop carefully or custom-order brassieres.At small D cup + 800cc implants, you may also become symptomatic with back pain, neck pain, shoulder grooves from bra straps, and ulnar nerve paresthesias from bra strap pressure on the nerves in your neck/shoulder area. These symptoms cause women with breasts of this size to seek breast reduction for relief of these debilitating problems, and often allows insurance to cover these breast reductions.Just so you know, I utilize 800cc implants in my practice reasonably commonly, but only in women whose anatomy allows excellent outcomes. Seek consultations with several ABPS-certified plastic surgeons who do lots of breast surgery and are not automatically dismissive of large(r) implants. Best wishes! Dr. Tholen